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1.
A mechanically flexible mat consisting of structurally amorphous SiO2 (glass) nanofibers was first prepared by electrospinning followed by pyrolysis under optimized conditions and procedures. Thereafter, two types of hybrid multi‐scale epoxy composites were fabricated via the technique of vacuum assisted resin transfer molding. For the first type of composites, six layers of conventional glass microfiber (GF) fabrics were infused with the epoxy resin containing shortened electrospun glass nanofibers (S‐EGNFs). For the second type of composites, five layers of electrospun glass nanofiber mats (EGNF‐mats) were sandwiched between six layers of conventional GF fabrics followed by the infusion of neat epoxy resin. For comparison, the (conventional) epoxy composites with six layers of GF fabrics alone were also fabricated as the control sample. Incorporation of EGNFs (i.e., S‐EGNFs and EGNF‐mats) into GF/epoxy composites led to significant improvements in mechanical properties, while the EGNF‐mats outperformed S‐EGNFs in the reinforcement of resin‐rich interlaminar regions. The composites reinforced with EGNF‐mats exhibited the highest mechanical properties overall; specifically, the impact absorption energy, interlaminar shear strength, flexural strength, flexural modulus, and work of fracture were (1097.3 ± 48.5) J/m, (42.2 ± 1.4) MPa, (387.1 ± 9.9) MPa, (12.9 ± 1.3) GPa, and (30.6 ± 1.8) kJ/m2, corresponding to increases of 34.6%, 104.8%, 65.4%, 33.0%, and 56.1% compared to the control sample. This study suggests that EGNFs (particularly flexible EGNF‐mats) would be an innovative type of nanoscale reinforcement for the development of high‐performance structural composites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42731.  相似文献   

2.
Green chemical method could be a promising route to achieve large scale synthesis of nanostructures for biomedical applications. Here, we describe a green chemical synthesis of silver nanoparticles (Ag NPs) on chitosan‐based electrospun nanofibers using Eucalyptus leaf extract. A series of silver salt (AgNO3) amounts were added to a certain composition of chitosan/polyethylene oxide aqueous acetic acid solution. The solutions were then electrospun to obtain nanofibrous mats and then, morphology and size of nanofibers were analyzed by scanning electron microscopy (SEM). Incubation of AgNO3‐containing mats into Eucalyptus leaf extract led to the formation of Ag NP clusters with average diameter of 91 ± 24 nm, depicted by SEM and transmission electron microscopy. Surface enhanced Raman spectroscopy also confirmed formation of Ag NPs on the nanofibers. The mats also showed antimicrobial activity against Escherichia coli and Staphylococcus aureus bacteria with bigger inhibition zone for extract‐exposed mats against S. aureus. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42133.  相似文献   

3.
One dimensional (1D) nanostructures and its derivatives can be manipulated to serve special functions like hollow structure, and higher surface area. 1D TiO2 nanotube-in-nanofibers (NF@NT) are developed through triaxial electrospinning followed by a calcination process. A blended solution of polyvinyl pyrrolidone and tetra-butyl titanate is used in outer and inner layers of nanofibers, respectively, while paraffin oil is used in the middle layer. The optimized triaxial nanofibers of 669.4 ± 52.43 nm are developed at 7.5 w/w% concentration, 28 kV applied voltage, and 24 cm spinning distance. TiO2 NF@NT structure is obtained through calcination of optimized triaxial nanofibers at 550°C. Subsequently, the morphology of TiO2 NF@NT and its uniform diameter distribution is confirmed through scanning electron microscopy. Fourier-transform infrared spectroscopy results indicates the formation of TiO2 NF@NT. X-Rays diffraction pattern peaks also reveals the presence of both anatase and rutile crystalline phases. The presence of only titanium (Ti) and oxygen (O) elements in the TiO2 NF@NT is confirmed through energy dispersive X-ray spectroscopy. Brunauer–Emmett–Teller analysis indicates that TiO2 NF@NT has a higher specific surface area of ~141.68 m2/g compared with the solid TiO2 nanofiber (~75.31 m2/g). This study can be adopted to develop TiO2 NF@NT for wide range of application.  相似文献   

4.
There is an extensive possibility of improving characteristics of fibers used in hard tissue engineering, being hydrophobic and less osteoconductive, resulting in the dynamic growth of new tissues. The current work focuses on the fabrication of nanofibers incorporated with titanium dioxide (TiO2) ''as osteoconductive'' and silver (Ag) ''as self-healing'' nanoparticles (NPs). The incorporation of AgNO3 by in situ method not only helped to impart the antibacterial activity but also changed the contact angle from 81 ± 03° in the case of pristine nanofibers to 74 ± 03°, 61 ± 03°, 50 ± 08°, and 39 ± 1.1°, in the composite scaffolds containing 0.01, 0.03, 0.05, and 0.07 M of Ag salts. The incubation in simulated body fluid at 37°C to induce mineralization on nanofiber scaffolds indicated Ca and P crystals' formation. The antibacterial activity showed significantly more toxicity toward E. coli (8.3 ± 0.9 mm) than S. aureus (1.2 ± 0.1 mm). Biocompatibility studies using MTT assay on the pre-osteoblasts showed that both TiO2 and Ag NPs present in the nanofibers are non-toxic to the bone-like cells. However, results show that a higher concentration of Ag NPs (i.e., 0.07 M) is toxic to cells growing. Finally, all the results suggest that the nanofiber scaffolds have considerable scope for future bone tissue engineering materials.  相似文献   

5.
In this work, different sol solutions with various titanium tetraisopropoxide (TIP)/glacial acetic acid ratios in 2‐propanol with 5 wt % poly(vinyl pyrrolidone) (PVP) (Mw = 360,000 g/mol) were prepared and electrospun. Composition of the prepared sols and as‐spun TiO2/PVP nanofibers were determined by Fourier transform infrared and Raman spectroscopy methods. Morphology of the electrospun TiO2/PVP nanofibers was studied by scanning electron microscopy and transmission electron microscopy (TEM) techniques. Rheometry measurements of the sol solutions showed decrease of viscosity upon the addition of TIP to the polymer solutions with constant polymer and acid concentrations. The sol solution having the lowest viscosity (at shear rate 10 s?1) but the highest TIP/glacial acetic acid ratio showed beaded nanofibers morphology when electrospun under 10 and 12 kV applied voltage while injection rate, needle tip to collector distance, and needle gauge were kept constant. However, smooth electrospun TiO2/PVP composite nanofibers with the average nanofibers diameters (148 ± 79 nm) were achieved under the same condition when applied voltage increased to 15 kV. TEM micrographs of the electrospun TiO2/PVP nanofiber showed that the TiO2 particles with continuous structure are formed at the middle of the nanofiber and distributed along its axis. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46337.  相似文献   

6.
In this work, we present the preparation of polylactic acid (PLLA)/polyaniline (PANI) conductive composite nanofibers mats. They are prepared by bulk oxidative solution polymerization of PANI onto electrospun non‐woven fibers mats of PLLA. The PANI ratio in the composite is about 70%w/w. Scanning electron microscopy (SEM) shows that PLLA nanofibers are randomly oriented, beads free with diameters of 186 ± 85 nm, The PLLA/PANI composite nanofibers diameter values are 518 ± 128 nm with a good adherence between PANI and PLLA nanofibers. DSC and XRD measurements reveal an amorphous structure of the electrospun PLLA fibers due to the rapid evaporization of the solvent. FTIR and UV–vis spectra reflect good mutual interactions between PANI and PLLA chains. The DC‐conductivities ( ) far better than other published ones for similar composites prepared by bulk oxidative solution polymerization of PANI onto other electrospun nanofiber mats or with electrospun nanofibers from a solution mixture of PLLA and PANI. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41618.  相似文献   

7.
Polyvinyl acetate (PVAc)/titanium dioxide (TiO2) hybrid nanofibers were fabricated by combining sol–gel process with electrospinning technology, which consisted of PVAc as organic segment and TiO2 as inorganic part. The surface structures of the PVAc/TiO2 hybrid nanofibrous mats were examined using scanning electron microscopy (SEM). The surface morphology and bulk structures of single nanofiber were investigated by atomic force microscopy (AFM) and transmission electron microscopy (TEM). Fourier transform infrared spectroscopy (FTIR) was employed to analyze the chemical structures of the PVAc/TiO2 hybrid nanofibers. SEM scanning revealed that the fibrous structure was formed. AFM observations presented a significant difference in the morphology of the nanofibers before and after hybridization. It was observed from TEM images that some black streaks with various lengths distributed in a nanofiber. The FTIR analysis indicated the newly formed associated hydrogen bond because of the hybrid effect between PVAc and TiO2 sol. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

8.
There is a contradiction in making completely opaque and white plastic film with a required high TiO2 filling fraction, which resulted in inefficient pigment utilization and high cost. Two methods were used here to overcome the contradiction. Firstly, TiO2 was grafted with poly(methyl methacrylate) (PMMA) by atom transfer radical polymerization to improve the pigment dispersion in poly(vinylidene) fluoride (PVDF). Secondly, minute amounts of carbon black (CB) were added into the PMMA‐g‐TiO2/PVDF system to enhance opacity and decrease TiO2 fraction. The structure, morphology, and properties of PMMA‐g‐TiO2 hybrid particles and composite films were investigated by FTIR, TEM, TGA, SEM, DMA, covering power meter, and UV/VIS spectrophotometer, etc. It was observed that PMMA‐g‐TiO2 was dispersed uniformly as individual particles in PVDF due to the good compatibility between PMMA and PVDF. Therefore, the opacity of PMMA‐g‐TiO2/PVDF films was markedly higher than unmodified‐TiO2/PVDF ones. Adding minute amounts of CB can significantly increase the opacity of the thin film due to its absorption effect on decreasing light transmittance. The contrast ratio (CR) of the PMMA‐g‐TiO2/PVDF film with 20 μm thickness and 25 vol % TiO2 was 97.67%, lower than the critical CR 98% for a complete opacity, however, the CR of sample with 10 vol % TiO2 was 98.1% as the CB concentration was 2 × 10?4 g/cm3, saved more than 15% TiO2. We proposed that a critical thickness d0 existed for the CB/PMMA‐g‐TiO2/PVDF composite films, under which the light reflectance increased as a function of thickness, otherwise, the reflectance kept constant. Besides, d0 could be decreased by increasing CB concentration. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43064.  相似文献   

9.
To develop a novel functional fibrous scaffold, a blend‐electrospinning technique was applied to transfer polyurethane/inorganic‐particles solutions into nanofibers, in which titanium dioxide, copper, or/and silver nanoparticles were used. The resultant nanofibers were subsequently characterized by means of scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and tensile mechanical test. Furthermore, the structural change and the thermal properties of the electrospun fabrics were examined by X‐ray diffraction and differential scanning calorimetry, respectively. Antibacterial performance of the resulting nanofibrous mats on Escherichia coli and Staphylococcus aureus was also measured. Experimental results have shown that when the ratio of polyurethane solution and titanium dioxide sol was in 3.5:1, 89.55% of the Escherichia coli and 82.35% of the Staphylococcus aureus bacteria were killed under a UV‐light activation. However, the introduction of silver or/and cuprum nanoparticles into the polyurethane/TiO2 (in the ratio of 3.5:1) nanofibers led to a significant improvement in their antibacterial ability without any photocatalysis.POLYM. COMPOS., 33:2045–2057, 2012. © 2012 Society of Plastics Engineers  相似文献   

10.
Poly(vinylidene fluoride) (PVDF) nanofibrous mats containing silver nanoparticles were prepared by electrospinning. The diameter of the nanofibers ranged between 100 and 300 nm, as revealed by scanning electron microscopy. The silver nanoparticles were dispersed, but some aggregation was observed with transmission electron microscopy. The content of silver nanoparticles incorporated into the PVDF nanofibrous mats was determined by inductively coupled plasma and X‐ray photoelectron spectroscopy. The antibacterial activities of the samples were evaluated with the colony‐counting method against Staphylococcus aureus (Gram‐positive) and Klebsiella pneumoniae (Gram‐negative) bacteria. The results indicate that the PVDF nanofibrous mats containing silver nanoparticles showed good antibacterial activity compared to the PVDF nanofiber control. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

11.
A photocatalytic activity ultrafiltration membrane (UFM) was prepared by the blending of a poly(vinylidene fluoride) (PVDF) polymer with mesoporous titanium dioxide (M‐TiO2) particles via the phase‐inversion method. The microstructure of the membrane and Ti element distribution were characterized by scanning electron microscopy and energy‐dispersive X‐ray spectroscopy. Their properties were also determined by thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy, tensile stress tests, contact angle tests, bovine serum albumin retention, water flux, and permeation flux. When the M‐TiO2 concentration reached 1 wt %, the thermal stability, mechanical properties, hydrophilicity, flux, and antifouling performance of the M‐TiO2/PVDF UFM were improved to an optimal value with the M‐TiO2 particles successfully entrapped and evenly distributed throughout the PVDF polymer matrix. Compared with the P25‐modified PVDF UFM (1 wt %), the M‐TiO2‐modified PVDF UFM (1 wt %) exhibited better photocatalytic activity and wonderful stability in the UV photocatalytic degradation of the organic dye Rhodamine B. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43427.  相似文献   

12.
N‐(4‐aminophenyl)aniline oxidative polymerization is optimized to produce polyaniline (PANI) free from carcinogenic and/or polluting coproducts. The resulting polymer is electrospun using polymethyl methacrylate (PMMA) as the supporting polymer, with different weight ratios (1:0, 4:1, 3:1, 2:1, 1:1, and 0.5:1 w/w PANI/PMMA). By rinsing with a selective solvent, PMMA is removed while maintaining the fibrous morphology. Ultrathin (65 ± 14 nm) and defect‐free PANI nanofiber mats are obtained for the blend containing a high relative content of PANI (2:1 w/w, namely F2:1). Two different solvents are tested to remove PMMA, namely acetone and isopropanol, the former giving better results, as highlighted by infrared spectroscopy (FTIR). X‐ray diffraction (XRD) demonstrates that the electrospun PANI is amorphous. The thin fiber mats are robust and sterilization both by autoclave and UV irradiation can be carried out. UV irradiation is preferred since no modification of the fibrous morphology is detectable. In vitro biocompatibility of the electrospun F2:1 fibers has been evaluated with SH‐SY5Y neuronal‐like cells. Indirect cytocompatibility tests show that no cytotoxic leachable is released by the electrospun mats at both short and longer times, while direct cytocompatibility investigations indicate that only F2:1 fibers washed in isopropanol do not reduce cell proliferation rate with respect to controls on tissue culture plates. Globally, these results suggest that the proposed electrospun nanostructures are promising materials for neuronal tissue engineering. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43885.  相似文献   

13.
An anti-bacterial filter was developed using poly vinylidene fluoride (PVDF) nanofibers using electrospinning method blended with silver nanoparticles (AgNO3) of varying weight percentages of filler. Polypropylene (PP) non-woven substrate was used as base material for collecting the nanofibers. It also acted as a barrier to protect the fibers. UV-visible spectroscopy and fourier transform infra red spectroscopy confirmed the uniform dispersion of silver nanoparticles throughout the nanofibers. The experiment was designed using Box–Behnken statistical tool through three different variables namely, PP non-woven sheets (GSM), electrospinning time (hours), concentration of silver (wt%) in 15 runs. Surface morphology was analyzed using scanning electron microscopy and atomic force microscopy. Thermogravimetric analysis was performed for the analyses of mass decomposition of the material. Bacterial filtration efficiency and anti-bacterial activity studies were tested against Staphylococcus aureus and Escherichia coli for both PVDF + 0?wt% Ag fibers and PVDF-Ag nanofibers. This research shows the bacterial filtration efficiency for the prepared PVDF-Ag nanofibers as 99.86%. The prepared nanofilter was shown providing greater possibilities towards the application for clean air management.

© Copyright 2019 American Association for Aerosol Research  相似文献   


14.
A major factor limiting the use of ultrafiltration (UF) membrane in water treatment process is the membrane fouling by natural organic matter such as humic acid (HA). In this work, neat PVDF and PVDF/TiO2 mixed‐matrix membranes were prepared and compared in terms of their antifouling properties. Two commercial types of TiO2 namely PC‐20 and P25 were embedded to prepare the mixed matrix membranes via in situ colloidal precipitation method. The contact angles for the mixed‐matrix membranes were slightly reduced while the zeta potential was increased (more negatively charged) compared with the neat membrane. Filtration of HA with the presence of Ca2+ demonstrated that mixed‐matrix membrane could significantly mitigate the fouling tendency compared with the neat membrane with flux ratio (J/J0) of 0.65, 0.70, and 0.82 for neat PVDF membrane, PVDF/TiO2 mixed‐matrix membrane embedded with P25 and PC‐20, respectively. PC‐20 with higher anatase polymorphs exhibited better antifouling properties due to its hydrophilicity nature. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

15.
Conductive nanofibers of poly(vinylidene fluoride) (PVDF) filled with polyaniline (PANi)‐coated multi‐wall carbon nanotubes (MWCNTs) were fabricated using the electrospinning technique. PANi is an intrinsically conductive polymer. The addition of PANi‐coated MWCNTs to PVDF created short conductive strands on the surface of the nanofibers, facilitating the formation of a conductive network in the transverse direction of the nanofibers. Piezoelectricity along with electric conductivity makes these PVDF nanofibers promising for applications such as sensors and actuators. Electrospun PVDF nanofiber mats had higher piezoelectricity than melt‐processed samples produced using traditional polymer processing techniques, such as compression molding. Spectroscopic imaging techniques were employed to study the effects of the filler and processing conditions on the nanofiber structure. X‐ray diffraction, Fourier transform infrared spectroscopy and differential scanning calorimetry results indicated a large increase in the β‐phase crystals of the PVDF nanofibers. This higher content of β‐phase crystals enhanced the piezoelectricity of the nanofibers. © 2015 Society of Chemical Industry  相似文献   

16.
In this work, a supercritical CO2 (SC-CO2) drying process for the formation of poly(vinylidenefluoride) (PVDF) aerogels containing amoxicillin has been tested. Experiments at pressures ranging between 150 and 250 bar and at temperatures ranging between 35 and 55 °C have been performed; then, the PVDF – isopropyl alcohol – N-methylpirrolidone solution at 10% (w/w) polymer has been selected for the addition of amoxicillin at concentrations between 10 and 30% (w/w) with respect to PVDF. Since amoxicillin is soluble in isopropyl alcohol, a quaternary solution has been obtained that produced PVDF aerogels characterized by drug coated nanometric fibers. A two step formation mechanism has been hypothesized that puts in evidence the non-interference of amoxicillin on PVDF gelation process and the heterogeneous amoxicillin precipitation on PVDF nanofibers. The coverage of nanofibers by amoxicillin turned the structure from hydrophobic to quasi-hydrophilic. A homogeneous drug distribution was obtained; a quasi-constant release rate and no burst effect were observed.  相似文献   

17.
《分离科学与技术》2012,47(16):2628-2638
ABSTRACT

Lignin liquefaction could be achieved under subcritical methanol; instead, the reported supercritical status using ZrO2/TiO2 nanofibers prepared by calcination of poly(vinyl-acetate)/titanium isopropoxide/zirconium isopropoxide electrospun mats. ZrO2 content in the final nanofibers has been adjusted at 0, 25, 50, 75 and 100 wt%. The nanofibers having 75 wt% ZrO2 showed the best catalytic activity toward lignin liquefaction, 57.1 wt% weight losses at 180°C. The results indicated that 2 h and 15 wt% are the optimum holding time and catalyst content, respectively. Liquefaction of sawdust was performed; more than 60 wt% of the solid waste was converted to simple alcohols at 300°C (supercritical conditions).  相似文献   

18.
Oil–water separation has attracted research interest due to the damages of oily wastewater caused to the environment and human beings. Electrospun fiber membrane has high oil–water separation performance. A nanofibers membrane with multi-stage roughness was prepared by electrospinning using poly(vinylidene fluoride)(PVDF)-silica blend solution as raw material. The result shows that the water contact angle (WCA) of the nanofibers membrane was promoted from 138.5 ± 1° to 150.0 ± 1.5° when the SiO2 content was increased from 0 to 3 wt%. The nanofibers membranes exhibited excellent separation efficiency (99 ± 0.1%) under gravity drive, with high separation flux of 1857 ± 101 L·m−2·h−1. More importantly, the obtained PVDF-SiO2 nanofibers membranes showed excellent multi-cycle performance and stable chemical resistance, which would make them great advantages for the practical application of oil–water separation.  相似文献   

19.
Poly(vinylidene fluoride) (PVDF) nanofibers were fabricated via electrospinning with an investigation of various ratios of binary solvents at different temperatures. The amount of acetone influenced the morphology. Scanning electron microscopy showed a PVDF membrane composed of smooth and unblemished fibers without beads and dark spots with small diameters of 201 ± 54 nm at a dimethylformamide‐to‐acetone ratio of 4:6. The temperature of pre‐thermal treatment from room temperature to 120 °C was investigated to promote the β crystalline phase in electrospun PVDF nanofibers. The result was characterized using Fourier transform infrared (FTIR) spectroscopy and X‐ray diffraction (XRD). PVDF solution prepared at 80 °C was used to increase the β crystalline phase of the electrospun PVDF nanofibers due to the transformation of α to β phase occurring during the spinning process and also bead‐free PVDF nanofibers were obtained. Differential scanning calorimetry revealed crystallization behavior corresponding with that determined using FTIR spectroscopy and XRD. Therefore, the solvent proportion and pretreatment temperature were observed to affect ultrafine nanofiber and crystalline structure of PVDF, respectively. © 2020 Society of Chemical Industry  相似文献   

20.
CdS/TiO2 NPs-decorated carbon nanofibers were introduced as a novel photocatalyst working under visible light radiation for the effective hydrolytic dehydrogenation of ammonia borane. Calcination of electrospun nanofiber mats composed of titanium tetraisopropoxide, poly (vinyl pyrrolidone) (PVP), and cadmium acetate dihydrate with a few drops of ammonium sulfide in argon atmosphere at 850 °C led to the production of CdS–TiO2 decorated carbon nanofibers. As-synthesized nanocomposite exhibited a strong photocatalytic activity for catalytic hydrolysis of ammonia–borane. The favorable electrons-transfer properties, better dispersion, high surface area, and adsorption property are the main features of nanocomposites that exhibit high catalytic efficiency.  相似文献   

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